The reason i know this, Is because i brought a loaf of. Hovis. Sunblest. Warburtons. Robertson's, Asda`s own, Tesco`s own, Morrisons own and Greggs, Placed them on the table in the shed and inspected them for Mould daily. Most lasted between 4 and 7 days but the Greggs stuff, Wow it`s unreal. it feels as fresh after a fortnight as it felt the day it was purchased, Possibly make you glow green at night if you ate to much of it though Lol.